Thank Ice Ages for Lakes

Map of the world's lakes with surface areas of 10 hectares or more. Dark blue areas reflect the high concentration of lakes in those regions. Credit: HydroLAB, McGill University

New research from the McGill University, published in Nature Communications, maps the distribution of our planet's lakes. It clearly shows how the last ice age shaped and formed many of the 1.4 million lakes, larger than 10 hectares, that contain 15% of all the lake water in the world. Dark blue color indicates density of lakes, and as the map shows the highest density can be found in the northern hemisphere, in regions previously covered in large ice sheets. The rest of the worlds lake water, 85%, can be found in the 10 largest lakes. About half of the lakes are freshwater and the other half are salt lakes.

Global distribution of water volume stored in lakes and reservoirs with a surface area of at least 10 ha. Source: Messager et al. (2016)

If we look at individual countries (table below) we find that Canada, Russia, USA, China, Sweden, Brazil and Norway rank in the top in regards to number of lakes and area (km2). While Russia stands out with the largest volume (103 km3) due to its many deep water lakes (e.g. lake baikal and lake vostok). Thinking in terms of drinking water, volume would probably be the most important parameter. But then again, distribution, pollution and many other factors come into play when determining access to safe drinking water.

Countries with most lakes

Country

Number of lakes (103)

Area (103 km2)

Volume (103 km3)

Canada

879.8

856.5

12.6

Russia

201.2

667.4

102.2

USA

102.5

340.3

23.5

China

23.8

81.0

1.0

Sweden

22.6

34.3

0.5

Brazil

20.9

31.4

0.2

Norway

20.0

13.9

0.3

The study only focuses on mapping out lakes it doesn’t say anything about what state these lakes are in etc. What we can tell is that the distribution of lakes is very uneven, very few along the equator and plenty in the north. Since water is such a critical resource and we’re already witnessing extreme heatwaves and extended droughts along the equator (e.g. southwestern US, Middle East) people are already realising that agriculture has to shift further north to survive, as do they.